This invention relates to new and useful improvements in magnetic instruments for determining direction. More particularly, it is concerned with the provision of a magnetic compass having a magnet bearing float which is self-centering and rotatable relative to an element of soft magnetic material spaced below it so as to align a pointer on the float with the earth's north magnetic pole and with the north point of a compass readout dial.
The conventional compass is an instrument for determining direction by allowing a bar magnet, commonly called a needle, balanced on a pin to pivot freely to align itself in the direction of the earth's magnetic field with the north-seeking pole of the magnet pointing toward the north magnetic pole of the earth.
A particular problem associated with the conventional needle compass is one of wear developing in the needle relative to the pivot. A jewel centered in the needle and resting upon a pivot tipped with a very hard material, such as iridium, is employed as a means tending to reduce this wear. Some compasses, such as the mariner's compass, which is also a needle compass, is subject to rolling with the ship in rough waters. A gimbal support allowing multiple axes of movement for the compass is provided with the mariner's compass for stabilizing it. Other faults commonly associated with the conventional needle compass arise from its complexity and the number of components it requires to employ the pivoted needle.
Accordingly, a general object of this invention is to provide a magnetic compass which does not have the faults commonly associated with the conventional needle compass.
A further object of the present invention is to provide a magnetic compass which functions efficiently without the need of a pivoted needle, a pivot pin or a gimbal. It accordingly does not have the problems of wear, or the need of the multiple components associated with the needle type compass.
A more particular object of this invention is to provide a self-centering needle-less compass, one which uses a magnetic float instead of a needle and employs a magnetic sphere for continually centering the float so that a pointer on the float pivots about an imaginary axis in becoming magnetically aligned with the earth's north-magnetic pole.
A noteworthy advantage of a compass embodying the present invention lies in the simplicity of its structure in that there is no complexity in the arrangement or association of its components, and in that the number of its components is relatively small as compared with the conventional needle compass.
A further advantage of a compass embodying the present invention is that it may be used alone, or it may be incorporated as a component of a surveyor's transit, an astronomer's sextant or a mariner's compass as well as other instruments.